Cavitation control system

ABSTRACT

Subject invention relates to a novel and improved apparatus for minimizing the phenomenon of cavitation and noise in a liquid circulating energy conversion device such as a water brake. Pressurized air or a suitable gas is mixed with the liquid that is circulated in the device so as to increase the pressure throughout the circulating liquid above the point where it will boil and cause cavitation. Pressure of the air or gas is automatically controlled by the amplitude of the noise in the device when cavitation occurs.

States Patent 1 Weinert CAVllTATION CONTROL SYSTEM [76] Inventor:

Cinnaminson, NJ. 08077 [22] Filed: Aug. 26, 1971 [211 App]. No.: 175,239

Eugene P. Weinert, 398 Willow Dr.,

[451 Sept. 25, 1973 Primary Examiner-C. J. Husar Att0rney-R. S. Sciascia, H. Hansen and A. A.

McGill [57] ABSTRACT Subject invention relates to a novel and improved apparatus for minimizing the phenomenon of cavitation and noise in a liquid circulating energy conversion device such as a water brake. Pressurized air or a suitable gas is mixed with the liquid that is circulated in the device so as to increase the pressure throughout the circulating liquid above the point where it will boil and cause cavitation. Pressure of the air or gas is automatically controlled by the amplitude of the noise in the device when cavitation occurs.

7 2 Claims, 2 Drawing Figures PATENTEDSEPZSSYS SflEET 2 BF 2 MENTOR. EUGENE P. WEINERT ATTORNEY @AVITATION CONTRGL SYSTEM The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Maintenance experience with liquid circulating energy conversion devices such as high speed hydraulic dynamometers or water brakes has been a serious problem. High shear forces on the liquid circulating through devices of this kind produce small evacuated areas at low pressure where the liquid tends to boil and then implode or cavitate as the prevalent high surrounding pressure condition is instantaneously restored. This cavitation process causes severe internal damage to the device in a relatively short period of operation, and considerable difficulty has been experienced in the past in minimizing the resulting necessary frequent and expensive repairs.

It is therefore a principal object of the invention to provide novel and improved apparatus for minimizing cavitation and noise in a liquid circulatory energy conversion device.

It is a further object of the invention to provide novel and improved apparatus for minimizing cavitation in a liquid circulatory device where a pressurized gas is mixed with the circulating liquid.

It is a further object of the invention to provide novel and improved apparatus for minimizing cavitation in a liquid circulatory device where the pressure of a gas mixed with the circulating liquid is automatically controlled by the noise of the cavitation in the device.

Other objects and many of the attendant advantages chambers 27 and annular fluid discharge chambers 29. Apertures 31 through each of the stator section vanes 21 provide fluid delivery passages between the fluid delivery chambers 25 and the impeller chambers 27. Fluid from the fluid supply source 33 is conducted into the fluid delivery chambers 25 in the casing through the fluid control valve 35 and conduit 37. Fluid exits from the fluid discharge chamber 29 through conduit 39 and the discharge control valve 41. Air or another gas is fed from a suitable pressurized source 43 through conduit 45 and control valve 47 into the fluid delivery chambers 25 of the casing. The prime mover 49 to be tested or controlled is coupled in any suitable manner to the shaft Sll of the rotor 15.

The microphone 53 is positioned near the braking device casing 5 where cavitation noise within the casing can be readily detected. The output circuit of the microphone 53 is coupled to the conventional electrical sound analyzing device 55 which passes bands of signals having octave frequencies of approximately 1,700, 3,400 and 6,800 cycles per second. The sound analyzing device 55 is coupled to the control computer device 57 which, in turn, electromechanically or otherwise suitably controls disposition of the compressed air or gas valve 47. The control computer device 57 is also regulated by the manual adjustment device 59 and by the sensor devices 61 and 63 respectively disposed in of this invention will be readily appreciated asthe same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a diagrammatic view partly in cross section and partly cutaway of a preferred embodiment of the invention; and

FIG. 2'is a perspective view of the liquid circulatory energy conversion device shown in H6. 1 with the upper half of the outer casing removed.

Referring now to the various figures of the drawing, it will be noted that the generally cylindrical portion3 of the casing or housing 5 of the invention is enclosed at opposite ends by the casing cover plates 7 which are secured to the cylindrical portion of the casingin any suitable manner. The Babbit metal water seal 9, the various knife edge oil seal 11 and the Babbit metal bearing 13 subassemblies are secured to the casing cover plates 7 and to one another preferably in the sequence shown in the drawing. The motor 15 of the braking device is rotatably mounted in the bearings 13 of the casing and includes the rotor sections 15a and 15b. Each rotor section has a plurality of radially disposed impeller vanes 17 that project outwardly from each lateral surface and form a plurality of concavities on both sides thereof. An annular stator section 119 is secured as shown within the casing 5 adjacent each rathe fluid delivery and fluid discharge chambers 25 and 29 to limit and control undesired pressure accumulations in the casing 5.

Inasmuch as the specific structural details of sound analyzer 55, the control computer 57 as well as the sensors 61 and 63 and control valve 47 are of conventional design and form no part of the invention, the same are not included herein for the sake of simplicity. For a full understanding of the invention, it need only be understood that the disposition of air pressure valve 47 is automatically controlled as the amplitude of the specified octave band sound signals vary.

In operation, after the prime mover 49 that is to be tested or controlled is mechanically coupled to the shaft of the rotor 15, a predetermined amount of fluid to absorb a given power output is supplied to the casing 5 through control valve 35. The prime mover 49 is then started up and the liquid in each of the concavities of rotor 15 is urged outwardly by centrifugal force. Movement of the liquid in this manner forces the liquid in the concavity of the juxtaposed stator sector 19 inwardly and vorticular circulations of liquid between the stator and rotor are developed. Shear of the circulating liquid and momentum exchange developed by the continuously changing direction and velocity of the liquid in the casing retards rotation of the rotor 15 and provides for absorption of energy of the prime mover 49. The continuous shearing and momentum exchange process also causes reduced pressure conditions at isolated locations in the casing such that the liquid tends to boil and produce gaseous bubbles. The bubbles then implode when subjected to surrounding high pressures and the phenomenon of cavitation results. Noise produced by the cavitation in the casing 5 is picked up by the microphone 53 and the 1,700, 3,400 and 6,800 cycle per second octave bands are passed through the sound analyzing device 55 to the control computer device 57. The output signal of the computer 57 then controls the pressure of the gas from its source 43 as it is mixed with the supply of liquid delivered to the casing 5 from liquid source 33. When the cavitation noise in the casing 5 increases, the pressure of the gas mixed into the liquid is increased. The increase in the pressure of the gas introduced into the casing increases the pressure throughout the casing to a point where the phenomenon of boiling and cavitation is substantially reduced or eliminated. The sensors 61 and 63 in the fluid delivery chamber 25 and the fluid discharge chamber 29 provide signals to the computer 57 such that safe pressure conditions in the casing 5 cannot be exceeded. The control device 59 allows the operator to manually adjust the pressure of the gas supplied to the casing when an adjustment is, for any reason, desired.

It is to be understood that although the invention is described hereinabove primarily in terms of application in a Froude type water brake or the like, it could be used in any type of liquid circulatory energy conversion system where cavitation occurs without departing from the spirit or scope of the invention.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A liquid circulatory energy conversion device comprising:

a generally cylindrical casing;

a rotor section mounted in said casing, said rotor section having a plurality of radially disposed impeller vanes and a plurality of radial surfaces;

a stator sectionsecured to the casing adjacent each radial surface of the rotor section, said stator section having a plurality of stator vanes that extend outwardly and radially from the interior of said casing;

means for introducing a liquid into said casing in the region between adjacent portions of said rotor and stator sections;

means for withdrawing said liquid from said casing;

and

means for reducing cavitation and noise within said casing during operation of said device including gas pressure control means sensitive to predetermined frequencies of noise created by cavitation in said casing for mixing a predetermined amount of gas at a predetermined automatically controlled pressure with said liquid.

2. A cavitation control system comprising:

an energy conversion device having a rotor and stator;

liquid conducting means for circulating a liquid through said energy conversion device; and

gas pressure means connected to said liquid conducting means for mixing a predetermined amount of gasat an automatically controlled pressure with said liquid, said gas pressure control means has filtering means sensitive to predetermined frequencies of noise created by cavitation for controlling the mixing of said predetermined amount of gas with said liquid. 

1. A liquid circulatory energy conversion device comprising: a generally cylindrical casing; a rotor section mounted in said casing, said rotor section having a plurality of radially disposed impeller vanes and a plurality of radial surfaces; a stator section secured to the casing adjacent each radial surface of the rotor section, said stator section having a plurality of stator vanes that extend outwardly and radially from the interior of said casing; means for introducing a liquid into said casing in the region between adjacent portions of said rotor and stator sections; means for withdrawing said liquid from said casing; and means for reducing cavitation and noise within said casing during operation of said device including gas pressure control means sensitive to predetermined frequencies of noise created by cavitation in said casing for mixing a predetermined amount of gas at a predetermined automatically controlled pressure with said liquid.
 2. A cavitation control system comprising: an energy conversion device having a rotor and stator; liquid conducting means for circulating a liquid through said energy conversion device; and gas pressure means connected to said liquid conducting means for mixing a predetermined amount of gas at an automatically controlled pressure with said liquid, said gas pressure control means has filtering means sensitive to predetermined frequencies of noise created by cavitation for controlling the mixing of said predetermined amount of gas with said liquid. 